Black starts a pawn advance on the queenside. White's position is very unpleasant.
15. f4g3 The best plan is to reduce Black's attacking potential. The queen is helpful for defending the king along the third rank. 15... c4f7 An interesting move, vacating the c4-square for the knight. 16. d4e5 It's necessary to capture the knight before it goes to c4. 16... f6e5  17. f1e2 